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Abstract:

A method for improving fuel efficiency, while maintaining or improving
wear protection, in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil having a HTHS viscosity of less
than 2.6 cP at 150° C. In one form, the formulated oil has a
composition that includes a lubricating oil base stock as a major
component, and zinc dialkyl dithio phosphate, a mixture of (i) at least
two alkali metal detergents, (ii) at least two alkaline earth metal
detergents, or (iii) one or more alkali metal detergents and one or more
alkaline earth metal detergents; and a viscosity index improver, as minor
components. The lubricating oil has a HTHS viscosity of less than 2.6 cP
at 150° C. The composition contains less than 2 weight percent of
the viscosity index improver, based on the total weight of the formulated
oil or lubricating engine oil.

Claims:

1. A method for improving fuel efficiency, while maintaining or improving
wear protection, in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil having a HTHS viscosity of less
than 2.6 cP at 150.degree. C., said formulated oil having a composition
comprising a lubricating oil base stock as a major component, and a zinc
dialkyl dithio phosphate, a mixture of (i) at least two alkali metal
detergents, (ii) at least two alkaline earth metal detergents, or (iii)
one or more alkali metal detergents and one or more alkaline earth metal
detergents; and a viscosity index improver, as minor components; wherein
said composition contains less than 2 weight percent of the viscosity
index improver, based on the total weight of the formulated oil; and
wherein said composition is sufficient for the formulated oil to pass
wear protection requirements of one or more engine tests selected from
TU3M, Sequence IIIG, Sequence IVA and OM646LA.

2. The method of claim 1 wherein the base oil comprises a Group I, Group
II, Group III, Group IV or Group V base oil.

4. The method of claim 1 wherein the alkali metal detergents and alkaline
earth metal detergents are selected from metallic salicylates and
sulfonates, and wherein the metallic salicylates and sulfonates are
selected from calcium and magnesium.

5. The method of claim 1 wherein the ZDDP is a secondary dialkyl dithio
phosphate.

6. The method of claim 1 wherein said composition contains less than 1
weight percent of the viscosity index improver, based on the total weight
of the formulated oil.

7. The method of claim 1 wherein the oil base stock is present in an
amount of from 70 weight percent to 95 weight percent, the zinc dialkyl
dithio phosphate (ZDDP) is present in an amount of from 0.4 weight
percent to 1.2 weight percent, and the mixture of (i) at least two alkali
metal detergents, (ii) at least two alkaline earth metal detergents, or
(iii) one or more alkali metal detergents and one or more alkaline earth
metal detergents, is present in an amount of from 1.0 weight percent to
6.0 weight percent, based on the total weight of the formulated oil.

8. The method of claim 1 wherein said composition contains less than 0.5
weight percent of the viscosity index improver, based on the total weight
of the formulated oil.

9. The method of claim 1 wherein the formulated oil has a HTHS viscosity
of less than 2.4 cP at 150.degree. C.

11. A lubricating engine oil having a composition comprising a
lubricating oil base stock as a major component, and a zinc dialkyl
dithio phosphate, a mixture of (i) at least two alkali metal detergents,
(ii) at least two alkaline earth metal detergents, or (iii) one or more
alkali metal detergents and one or more alkaline earth metal detergents;
and a viscosity index improver, as minor components; wherein said
lubricating engine oil has a HTHS viscosity of less than 2.6 cP at
150.degree. C.; wherein said composition contains less than 2 weight
percent of the viscosity index improver, based on the total weight of the
lubricating engine oil; and wherein said composition is sufficient for
the lubricating engine oil to pass wear protection requirements of one or
more engine tests selected from TU3M, Sequence IIIG, Sequence IVA and
OM646LA.

12. The lubricating engine oil of claim 11 wherein the oil base stock
comprises a Group I, Group II Group III, Group IV or Group V base oil.

14. The lubricating engine oil of claim 11 wherein the alkali metal
detergents and alkaline earth metal detergents are selected from metallic
salicylates and sulfonates, and wherein the metallic salicylates and
sulfonates are selected from calcium and magnesium.

16. The lubricating engine oil of claim 11 wherein said composition
contains less than 1 weight percent of the viscosity index improver,
based on the total weight of the lubricating engine oil.

17. The lubricating engine oil of claim 11 wherein the oil base stock is
present in an amount of from 70 weight percent to 95 weight percent, the
zinc dialkyl dithio phosphate (ZDDP) is present in an amount of from 0.4
weight percent to 1.2 weight percent, and the mixture of (i) at least two
alkali metal detergents, (ii) at least two alkaline earth metal
detergents, or (iii) one or more alkali metal detergents and one or more
alkaline earth metal detergents, is present in an amount of from 1.0
weight percent to 6.0 weight percent, based on the total weight of the
lubricating engine oil.

18. The lubricating engine oil of claim 11 wherein said composition
contains less than 0.5 weight percent of the viscosity index improver,
based on the total weight of the lubricating engine oil.

19. The lubricating engine oil of claim 11 which has a HTHS viscosity of
less than 2.4 cP at 150.degree. C.

[0003] Fuel efficiency requirements for passenger vehicles are becoming
increasingly more stringent. New legislation in the United States and
European Union within the past few years has set fuel economy and
emissions targets not readily achievable with today's vehicle and
lubricant technology. In order to improve lubricant fuel economy
performance, reduction of viscosity is typically the best path; however,
present day lubricant oils with a HTHS (ASTM D4683) viscosity of less
than 2.6 cP at 150° C. would not be expected to be able to provide
acceptable passenger vehicle engine durability performance.

[0004] HTHS is the measure of a lubricant's viscosity under conditions
that simulate severe engine operation. Under high temperatures and high
stress conditions, viscosity index improver degradation can occur. As
this happens, the viscosity of the oil decreases which may lead to
increased engine wear.

[0005] A viscosity index improver is typically added to engine oil in
order to provide appropriate viscosity at high and low temperatures and
thereby widen the application temperature range. High molecular weight
polymers are widely used as viscosity index improvers. The high molecular
weight polymer-based viscosity index improver has the typical property of
such improvers; that is, a temporary viscosity decrease due to
orientation, etc., occurs during operation at high speed/high load or
under other high shear conditions, and irreversible viscosity decrease
occurs due to molecular weight decrease as a result of chopping of the
polymer molecules when the shear conditions become severe. Also, when the
viscosity of the engine oil is reduced, the engine oil film itself
becomes thinner, and the opportunity for increased engine wear arises.
Therefore, for engine oils in which a viscosity index improver is added,
if the viscosity is reduced by simply reducing the viscosity of the base
oil, it is not possible to guarantee the oil film under high shear
conditions, and engine wear can easily occur.

[0006] Despite the advances in lubricant oil formulation technology, there
exists a need for an engine oil lubricant that effectively improves fuel
economy while providing superior antiwear performance, and has the
capability to do so through reduction or removal of viscosity index
improvers.

SUMMARY

[0007] This disclosure relates in part to a method for improving fuel
efficiency, while maintaining or improving wear protection, in an engine
lubricated with a lubricating oil by reducing the amount of a viscosity
index improver in the lubricating oil sufficient for the lubricating oil
to have a HTHS viscosity of less than 2.6 cP at 150° C.

[0008] This disclosure also relates in part to a method for improving fuel
efficiency, while maintaining or improving wear protection, in an engine
lubricated with a lubricating oil by using as the lubricating oil a
formulated oil having a HTHS viscosity of less than 2.6 cP at 150°
C. The formulated oil has a composition that comprises a lubricating oil
base stock as a major component, and zinc dialkyl dithio phosphate, a
mixture of (i) at least two alkali metal detergents, (ii) at least two
alkaline earth metal detergents, or (iii) one or more alkali metal
detergents and one or more alkaline earth metal detergents; and a
viscosity index improver, as minor components. The composition contains
less than 2 weight percent of the viscosity index improver, based on the
total weight of the formulated oil. The composition is sufficient for the
formulated oil to pass wear protection requirements of one or more engine
tests selected from TU3M, Sequence IIIG, Sequence IVA and OM646LA.

[0009] This disclosure further relates in part to a lubricating engine oil
having a composition comprising a lubricating oil base stock as a major
component, and a zinc dialkyl dithio phosphate, a mixture of (i) at least
two alkali metal detergents, (ii) at least two alkaline earth metal
detergents, or (iii) one or more alkali metal detergents and one or more
alkaline earth metal detergents, e.g., magnesium sulfonate and calcium
salicylate; and a viscosity index improver, as minor components. The
lubricating engine oil has a HTHS viscosity of less than 2.6 cP at
150° C. The composition contains less than 2 weight percent of the
viscosity index improver, based on the total weight of the lubricating
engine oil. The composition is sufficient for the lubricating engine oil
to pass wear protection requirements of one or more engine tests selected
from TU3M, Sequence IIIG, Sequence IVA and OM646LA.

[0010] This disclosure yet further relates in part to a method for
improving fuel efficiency, while maintaining or improving wear
protection, in an engine lubricated with a lubricating oil by using as
the lubricating oil a formulated oil having a HTHS viscosity of less than
2.6 cP at 150° C. The formulated oil has a composition that
comprises a lubricating oil base stock as a major component, and zinc
dialkyl dithio phosphate, and a mixture of (i) at least two alkali metal
detergents, (ii) at least two alkaline earth metal detergents, or (iii)
one or more alkali metal detergents and one or more alkaline earth metal
detergents, as minor components. The composition can optionally contain a
viscosity index improver in an amount less than 2 weight percent, based
on the total weight of the formulated oil. The composition is sufficient
for the formulated oil to pass wear protection requirements of one or
more engine tests selected from TU3M, Sequence IIIG, Sequence IVA and
OM646LA.

[0011] This disclosure also relates in part to a lubricating engine oil
having a composition comprising a lubricating oil base stock as a major
component, and a zinc dialkyl dithio phosphate, and a mixture of (i) at
least two alkali metal detergents, (ii) at least two alkaline earth metal
detergents, or (iii) one or more alkali metal detergents and one or more
alkaline earth metal detergents, e.g., magnesium sulfonate and calcium
salicylate, as minor components. The lubricating engine oil has a HTHS
viscosity of less than 2.6 cP at 150° C. The composition can
optionally contain a viscosity index improver in an amount less than 2
weight percent, based on the total weight of the formulated oil. The
composition is sufficient for the formulated oil to pass wear protection
requirements of one or more engine tests selected from TU3M, Sequence
IIIG, Sequence IVA and OM646LA.

[0012] In accordance with this disclosure, improvements in fuel economy
are obtained without sacrificing engine durability by a reduction of HTHS
viscosity to a level less than 2.6 cP through reduction or removal of
viscosity modifiers. Engine wear protection is maintained even when a
viscosity modifier is reduced or removed from the engine oil formulation,
leading to substantially lower HTHS viscosities, e.g., 2.6 cP or lower at
150° C.

[0013] Other objects and advantages of the present disclosure will become
apparent from the detailed description that follows.

DETAILED DESCRIPTION

[0014] All numerical values within the detailed description and the claims
herein are modified by "about" or "approximately" the indicated value,
and take into account experimental error and variations that would be
expected by a person having ordinary skill in the art.

[0015] It has now been found that improved fuel efficiency can be
attained, while wear protection is maintained or improved, in an engine
lubricated with a lubricating oil by using as the lubricating oil a
formulated oil having a HTHS viscosity of less than 2.6 cP at 150°
C. The formulated oil comprises a lubricating oil base stock as a major
component, a zinc dialkyl dithio phosphate, and a mixture of (i) at least
two alkali metal detergents, (ii) at least two alkaline earth metal
detergents, or (iii) one or more alkali metal detergents and one or more
alkaline earth metal detergents; and a viscosity index improver, as minor
components. The lubricating oils of this disclosure are particularly
advantageous as passenger vehicle engine oil (PVEO) products.

[0017] The engine lubricating oil of the present disclosure has a HTHS
viscosity of less than 2.6 cP at 150° C., preferably less than 2.4
cP at 150° C., and more preferably less than 2.2 cP at 150°
C.

[0018] The lubricating engine oils of this disclosure have a composition
sufficient to pass wear protection requirements of one or more engine
tests selected from TU3M, Sequence IIIG, Sequence IVA, OM646LA and
others.

Lubricating Oil Base Stocks

[0019] A wide range of lubricating base oils is known in the art.
Lubricating base oils that are useful in the present disclosure are both
natural oils, and synthetic oils, and unconventional oils (or mixtures
thereof) can be used unrefined, refined, or rerefined (the latter is also
known as reclaimed or reprocessed oil). Unrefined oils are those obtained
directly from a natural or synthetic source and used without added
purification. These include shale oil obtained directly from retorting
operations, petroleum oil obtained directly from primary distillation,
and ester oil obtained directly from an esterification process. Refined
oils are similar to the oils discussed for unrefined oils except refined
oils are subjected to one or more purification steps to improve at least
one lubricating oil property. One skilled in the art is familiar with
many purification processes. These processes include solvent extraction,
secondary distillation, acid extraction, base extraction, filtration, and
percolation. Rerefined oils are obtained by processes analogous to
refined oils but using an oil that has been previously used as a feed
stock.

[0020] Groups I, II, III, IV and V are broad base oil stock categories
developed and defined by the American Petroleum institute (API
Publication 1509; www.API.org) to create guidelines for lubricant base
oils. Group I base stocks have a viscosity index of between 80 to 120 and
contain greater than 0.03% sulfur and/or less than 90% saturates. Group
II base stocks have a viscosity index of between 80 to 120, and contain
less than or equal to 0.03% sulfur and greater than or equal to 90%
saturates. Group III stocks have a viscosity index greater than 120 and
contain less than or equal to 0.03% sulfur and greater than 90%
saturates. Group IV includes polyalphaolefins (PAO). Group V base stock
includes base stocks not included in Groups I-IV. The table below
summarizes properties of each of these five groups.

TABLE-US-00001
Base Oil Properties
Saturates Sulfur Viscosity Index
Group I <90 and/or >0.03% and ≧80 and <120
Group II ≧90 and ≦0.03% and ≧80 and <120
Group III ≧90 and ≦0.03% and ≧120
Group IV Includes polyalphaolefins (PAO) and GTL products
Group V All other base oil stocks not included in Groups I, II, III or IV

[0021] Natural oils include animal oils, vegetable oils (castor oil and
lard oil, for example), and mineral oils. Animal and vegetable oils
possessing favorable thermal oxidative stability can be used. Of the
natural oils, mineral oils are preferred. Mineral oils vary widely as to
their crude source, for example, as to whether they are paraffinic,
naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or
shale are also useful. Natural oils vary also as to the method used for
their production and purification, for example, their distillation range
and whether they are straight run or cracked, hydrorefined, or solvent
extracted.

[0022] Group II and/or Group III hydroprocessed or hydrocracked
basestocks, including synthetic oils such as polyalphaolefins, alkyl
aromatics and synthetic esters are also well known basestock oils.

[0024] The number average molecular weights of the PAOs, which are known
materials and generally available on a major commercial scale from
suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical
Company, BP, and others, typically vary from 250 to 3,000, although PAO's
may be made in viscosities up to 100 cSt (100° C.). The PAOs are
typically comprised of relatively low molecular weight hydrogenated
polymers or oligomers of alphaolefins which include, but are not limited
to, C2 to C32 alphaolefins with the C8 to C16
alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like, being
preferred. The preferred polyalphaolefins are poly-1-octene,
poly-1-decene and poly-1-dodecene and mixtures thereof and mixed
olefin-derived polyolefins. However, the dimers of higher olefins in the
range of C14 to C18 may be used to provide low viscosity
basestocks of acceptably low volatility. Depending on the viscosity grade
and the starting oligomer, the PAOs may be predominantly trimers and
tetramers of the starting olefins, with minor amounts of the higher
oligomers, having a viscosity range of 1.5 to 12 cSt.

[0025] The PAO fluids may be conveniently made by the polymerization of an
alphaolefin in the presence of a polymerization catalyst such as the
Friedel-Crafts catalysts including, for example, aluminum trichloride,
boron trifluoride or complexes of boron trifluoride with water, alcohols
such as ethanol, propanol or butanol, carboxylic acids or esters such as
ethyl acetate or ethyl propionate. For example the methods disclosed by
U.S. Pat. No. 4,149,178 or 3,382,291 may be conveniently used herein.
Other descriptions of PAO synthesis are found in the following U.S. Pat.
Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156;
4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the
C14 to C18 olefins are described in U.S. Pat. No. 4,218,330.

[0026] The hydrocarbyl aromatics can be used as base oil or base oil
component and can be any hydrocarbyl molecule that contains at least 5%
of its weight derived from an aromatic moiety such as a benzenoid moiety
or naphthenoid moiety, or their derivatives. These hydrocarbyl aromatics
include alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl
naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylated
thiodiphenol, and the like. The aromatic can be mono-alkylated,
dialkylated, polyalkylated, and the like. The aromatic can be mono- or
poly-functionalized. The hydrocarbyl groups can also be comprised of
mixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups,
cycloalkenyl groups and other related hydrocarbyl groups. The hydrocarbyl
groups can range from C6 up to C60 with a range of C8 to
C20 often being preferred. A mixture of hydrocarbyl groups is often
preferred, and up to three such substituents may be present. The
hydrocarbyl group can optionally contain sulfur, oxygen, and/or nitrogen
containing substituents. The aromatic group can also be derived from
natural (petroleum) sources, provided at least 5% of the molecule is
comprised of an above-type aromatic moiety. Viscosities at 100° C.
of approximately 3 cSt to 50 cSt are preferred, with viscosities of
approximately 3.4 cSt to 20 cSt often being more preferred for the
hydrocarbyl aromatic component. In one embodiment, an alkyl naphthalene
where the alkyl group is primarily comprised of 1-hexadecene is used.
Other alkylates of aromatics can be advantageously used. Naphthalene or
methyl naphthalene, for example, can be alkylated with olefins such as
octene, decene, dodecene, tetradecene or higher, mixtures of similar
olefins, and the like. Useful concentrations of hydrocarbyl aromatic in a
lubricant oil composition can be 2% to 25%, preferably 4% to 20%, and
more preferably 4% to 15%, depending on the application.

[0029] Suitable synthetic ester components include the esters of
trimethylol propane, trimethylol butane, trimethylol ethane,
pentaerythritol and/or dipentaerythritol with one or more monocarboxylic
acids containing from 5 to 10 carbon atoms. These esters are widely
available commercially, for example, the Mobil P-41 and P-51 esters of
ExxonMobil Chemical Company).

[0030] Other useful fluids of lubricating viscosity include
non-conventional or unconventional base stocks that have been processed,
preferably catalytically, or synthesized to provide high performance
lubrication characteristics.

[0031] Non-conventional or unconventional base stocks/base oils include
one or more of a mixture of base stock(s) derived from one or more
Gas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate base
stock(s) derived from natural wax or waxy feeds, mineral and or
non-mineral oil waxy feed stocks such as slack waxes, natural waxes, and
waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy
raffinate, hydrocrackate, thermal crackates, or other mineral, mineral
oil, or even non-petroleum oil derived waxy materials such as waxy
materials received from coal liquefaction or shale oil, and mixtures of
such base stocks.

[0033] GTL base stock(s) and/or base oil(s) derived from GTL materials,
especially, hydrodewaxed or hydroisomerized/followed by cat and/or
solvent dewaxed wax or waxy feed, preferably F-T material derived base
stock(s) and/or base oil(s), are characterized typically as having
kinematic viscosities at 100° C. of from 2 mm2/s to 50
mm2/s (ASTM D445). They are further characterized typically as
having pour points of -5° C. to -40° C. or lower (ASTM
D97). They are also characterized typically as having viscosity indices
of 80 to 140 or greater (ASTM D2270).

[0034] In addition, the GTL base stock(s) and/or base oil(s) are typically
highly paraffinic (>90% saturates), and may contain mixtures of
monocycloparaffins and multicycloparaffins in combination with non-cyclic
isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content
in such combinations varies with the catalyst and temperature used.
Further, GTL base stock(s) and/or base oil(s) typically have very low
sulfur and nitrogen content, generally containing less than 10 ppm, and
more typically less than 5 ppm of each of these elements. The sulfur and
nitrogen content of GTL base stock(s) and/or base oil(s) obtained from
F-T material, especially F-T wax, is essentially nil. In addition, the
absence of phosphorous and aromatics make this materially especially
suitable for the formulation of low SAP products.

[0035] The term GTL base stock and/or base oil and/or wax isomerate base
stock and/or base oil is to be understood as embracing individual
fractions of such materials of wide viscosity range as recovered in the
production process, mixtures of two or more of such fractions, as well as
mixtures of one or two or more low viscosity fractions with one, two or
more higher viscosity fractions to produce a blend wherein the blend
exhibits a target kinematic viscosity.

[0037] In addition, the GTL base stock(s) and/or base oil(s) are typically
highly paraffinic (>90% saturates), and may contain mixtures of
monocycloparaffins and multicycloparaffins in combination with non-cyclic
isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content
in such combinations varies with the catalyst and temperature used.
Further, GTL base stock(s) and/or base oil(s) and hydrodewaxed, or
hydroisomerized/cat (and/or solvent) dewaxed base stock(s) and/or base
oil(s) typically have very low sulfur and nitrogen content, generally
containing less than 10 ppm, and more typically less than 5 ppm of each
of these elements. The sulfur and nitrogen content of GTL base stock(s)
and/or base oil(s) obtained from F-T material, especially F-T wax, is
essentially nil. In addition, the absence of phosphorous and aromatics
make this material especially suitable for the formulation of low sulfur,
sulfated ash, and phosphorus (low SAP) products.

[0038] Base oils for use in the formulated lubricating oils useful in the
present disclosure are any of the variety of oils corresponding to API
Group I, Group II, Group III, Group IV, and Group V oils and mixtures
thereof, preferably API Group II, Group III, Group IV, and Group V oils
and mixtures thereof, more preferably the Group III to Group V base oils
due to their exceptional volatility, stability, viscometric and
cleanliness features. Minor quantities of Group I stock, such as the
amount used to dilute additives for blending into formulated lube oil
products, can be tolerated but should be kept to a minimum, i.e. amounts
only associated with their use as diluent/carrier oil for additives used
on an "as-received" basis. Even in regard to the Group II stocks, it is
preferred that the Group II stock be in the higher quality range
associated with that stock, i.e. a Group II stock having a viscosity
index in the range 100<VI<120.

[0039] The base oil constitutes the major component of the engine oil
lubricant composition of the present disclosure and typically is present
in an amount ranging from 50 to 99 weight percent, preferably from 70 to
95 weight percent, and more preferably from 85 to 95 weight percent,
based on the total weight of the composition. The base oil may be
selected from any of the synthetic or natural oils typically used as
crankcase lubricating oils for spark-ignited and compression-ignited
engines. The base oil conveniently has a kinematic viscosity, according
to ASTM standards, of 2.5 cSt to 12 cSt (or mm2/s) at 100° C.
and preferably of 2.5 cSt to 9 cSt (or mm2/s) at 100° C.
Mixtures of synthetic and natural base oils may be used if desired.

Antiwear Additive

[0040] A metal alkylthiophosphate and more particularly a metal dialkyl
dithio phosphate in which the metal constituent is zinc, or zinc dialkyl
dithio phosphate (ZDDP) is an essential component of the lubricating oils
of this disclosure. ZDDP can be primary, secondary or mixtures thereof.
ZDDP compounds generally are of the formula
Zn[SP(S)(OR1)(OR2)]2 where R1 and R2 are
C1-C18 alkyl groups, preferably C2-C12 alkyl groups.
These alkyl groups may be straight chain or branched.

[0041] Preferable zinc dithiophosphates which are commercially available
include secondary zinc dithiophosphates such as those available from for
example, The Lubrizol Corporation under the trade designations "LZ 677A",
"LZ 1095" and "LZ 1371", from for example Chevron Oronite under the trade
designation "OLOA 262" and from for example Afton Chemical under the
trade designation "HITEC 7169".

[0042] The ZDDP is typically used in amounts of from 0.4 weight percent to
1.2 weight percent, preferably from 0.5 weight percent to 1.0 weight
percent, and more preferably from 0.6 weight percent to 0.8 weight
percent, based on the total weight of the lubricating oil, although more
or less can often be used advantageously. Preferably, the ZDDP is a
secondary ZDDP and present in an amount of from 0.6 to 1.0 weight percent
of the total weight of the lubricating oil.

Detergent Mixture Additive

[0043] A detergent mixture containing (i) at least two alkali metal
detergents, (ii) at least two alkaline earth metal detergents, or (iii)
one or more alkali metal detergents and one or more alkaline earth metal
detergents, is an essential component in the lubricating oils of this
disclosure. A typical detergent is an anionic material that contains a
long chain hydrophobic portion of the molecule and a smaller anionic or
oleophobic hydrophilic portion of the molecule. The anionic portion of
the detergent is typically derived from an organic acid such as a sulfur
acid, carboxylic acid, phosphorous acid, phenol, or mixtures thereof. The
counterion is typically an alkaline earth or alkali metal.

[0044] Salts that contain a substantially stoichiometric amount of the
metal are described as neutral salts and have a total base number (TBN,
as measured by ASTM D2896) of from 0 to 80. Many compositions are
overbased, containing large amounts of a metal base that is achieved by
reacting an excess of a metal compound (a metal hydroxide or oxide, for
example) rich an acidic gas (such as carbon dioxide). Useful detergents
can be neutral, mildly overbased, or highly overbased.

[0045] It is desirable for at least some detergent used in the detergent
mixture to be overbased. Overbased detergents help neutralize acidic
impurities produced by the combustion process and become entrapped in the
oil. Typically, the overbased material has a ratio of metallic ion to
anionic portion of the detergent of 1.05:1 to 50:1 on an equivalent
basis. More preferably, the ratio is from 4:1 to 25:1. The resulting
detergent is an overbased detergent that will typically have a TBN of 150
or higher, often 250 to 450 or more. Preferably, the overbasing cation is
sodium, calcium, or magnesium. A mixture of detergents of differing TBN
can be used in the present disclosure.

[0046] Preferred detergent mixtures include at least two of the alkali or
alkaline earth metal salts of sulfonates, phenates, carboxylates,
phosphates, and salicylates, e.g., a mixture of magnesium sulfonate and
calcium salicylate.

[0047] Sulfonates may be prepared from sulfonic acids that are typically
obtained by sulfonation of alkyl substituted aromatic hydrocarbons.
Hydrocarbon examples include those obtained by alkylating benzene,
toluene, xylene, naphthalene, biphenyl and their halogenated derivatives
(chlorobenzme, chlorotoluene, and chloronaphthalene, for example). The
alkylating agents typically have 3 to 70 carbon atoms. The alkaryl
sulfonates typically contain 9 to 80 carbon or more carbon atoms, more
typically from 16 to 60 carbon atoms.

[0048] Alkaline earth phenates are another useful class of detergent.
These detergents can be made by reacting alkaline earth metal hydroxide
or oxide (CaO, Ca(OH)2, BaO, Ba(OH)2, MgO, Mg(OH)2, for
example) with an alkyl phenol or sulfurized alkylphenol. Useful alkyl
groups include straight chain or branched C1-C30 alkyl groups,
preferably, C4-C20. Examples of suitable phenols include
isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the
like. It should be noted that starting alkylphenols may contain more than
one alkyl substituent that are each independently straight chain or
branched. When a non-sulfurized alkylphenol is used, the sulfurized
product may be obtained by methods well known in the art. These methods
include heating a mixture of alkylphenol and sulfurizing agent (including
elemental sulfur, sulfur halides such as sulfur dichloride, and the like)
and then reacting the sulfurized phenol with an alkaline earth metal
base.

[0049] Metal salts of carboxylic acids are also useful as detergents.
These carboxylic acid detergents may be prepared by reacting a basic
metal compound with at least one carboxylic acid and removing free water
from the reaction product. These compounds may be overbased to produce
the desired TBN level. Detergents made from salicylic acid are one
preferred class of detergents derived from carboxylic acids. Useful
salicylates include long chain alkyl salicylates. One useful family of
compositions is of the formula

##STR00001##

where R is an alkyl group having 1 to 30 carbon atoms, n is an integer
from 1 to 4, and M is an alkaline earth metal. Preferred R groups are
alkyl chains of at least C11, preferably C13 or greater. R may
be optionally substituted with substituents that do not interfere with
the detergent's function, M is preferably, calcium, magnesium, or barium.
More preferably, M is calcium.

[0050] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal
salts of the hydrocarbyl-substituted salicylic acids may be prepared by
double decomposition of a metal salt in a polar solvent such as water or
alcohol.

[0051] Alkaline earth metal phosphates are also used as detergents and are
known in the art.

[0052] Detergents may be simple detergents or what is known as hybrid or
complex detergents. The latter detergents can provide the properties of
two detergents without the need to blend separate materials. See U.S.
Pat. No. 6,034,039.

[0054] The detergent mixture concentration in the lubricating oils of this
disclosure can range from 1.0 to 6.0 weight percent, preferably 2.0 to
5.0 weight percent, and more preferably from 2.0 weight percent to 4.0
weight percent, based on the total weight of the lubricating oil.

[0056] The types and quantities of performance additives used in
combination with the instant disclosure in lubricant compositions are not
limited by the examples shown herein as illustrations.

Dispersants

[0057] During engine operation, oil-insoluble oxidation byproducts are
produced. Dispersants help keep these byproducts in solution, thus
diminishing their deposition on metal surfaces. Dispersants used in the
formulation of the lubricating oil may be ashless or ash-forming in
nature. Preferably, the dispersant is ashless. So-called ashless
dispersants are organic materials that form substantially no ash upon
combustion. For example, non-metal-containing or borated metal-free
dispersants are considered ashless. In contrast, metal-containing
detergents discussed above form ash upon combustion.

[0058] Suitable dispersants typically contain a polar group attached to a
relatively high molecular weight hydrocarbon chain. The polar group
typically contains at least one element of nitrogen, oxygen, or
phosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

[0059] Chemically, many dispersants may be characterized as phenates,
sulfonates, sulfurized phenates, salicylates, naphthenates, stearates,
carbamates, thiocarbamates, phosphorus derivatives. A particularly useful
class of dispersants are the alkenylsuccinic derivatives, typically
produced by the reaction of a long chain hydrocarbyl substituted succinic
compound, usually a hydrocarbyl substituted succinic anhydride, with a
polyhydroxy or polyamino compound. The long chain hydrocarbyl group
constituting the oleophilic portion of the molecule which confers
solubility in the oil, is normally a polyisobutylene group. Many examples
of this type of dispersant are well known commercially and in the
literature. Exemplary U.S. patents describing such dispersants are U.S.
Pat. Nos. 3,172,892; 3,215,707; 3,219,666; 3,316,177; 3,341,542;
3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374 and
4,234,435. Other types of dispersant are described in U.S. Pat. Nos.
3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555;
3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882;
4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849;
3,702,300; 4,100,082; 5,705,458. A further description of dispersants may
be found, for example, in European Patent Application No, 471 071, to
which reference is made for this purpose.

[0060] Hydrocarbyl-substituted succinic acid and hydrocarbyl-substituted
succinic anhydride derivatives are useful dispersants. In particular,
succinimide, succinate esters, or succinate ester amides prepared by the
reaction of a hydrocarbon-substituted succinic acid compound preferably
having at least 50 carbon atoms in the hydrocarbon substituent, with at
least one equivalent of an alkylene amine are particularly useful.

[0061] Succinimides are formed by the condensation reaction between
hydrocarbyl substituted succinic anhydrides and amines. Molar ratios can
vary depending on the polyamine. For example, the molar ratio of
hydrocarbyl substituted succinic anhydride to TEPA can vary from 1:1 to
5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936;
3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616, 3,948,800; and
Canada Patent No. 1,094,044.

[0062] Succinate esters are formed by the condensation reaction between
hydrocarbyl substituted succinic anhydrides and alcohols or polyols.
Molar ratios can vary depending on the alcohol or polyol used. For
example, the condensation product of a hydrocarbyl substituted succinic
anhydride and pentaerythritol is a useful dispersant.

[0063] Succinate ester amides are formed by condensation reaction between
hydrocarbyl substituted succinic anhydrides and alkanol amines. For
example, suitable alkanol amines include ethoxylated polyalkylpolyamines,
propoxylated polyalkylpolyamines and polyalkenylpolyamines such as
polyethylene polyamines. One example is propoxylated
hexamethylenediamine. Representative examples are shown in U.S. Pat. No.
4,426,305.

[0064] The molecular weight of the hydrocarbyl substituted succinic
anhydrides used in the preceding paragraphs will typically range between
800 and 2,500. The above products can be post-reacted with various
reagents such as sulfur, oxygen, formaldehyde, carboxylic acids such as
oleic acid. The above products can also be post reacted with boron
compounds such as boric acid, borate esters or highly borated
dispersants, to form borated dispersants generally having from 0.1 to 5
moles of boron per mole of dispersant reaction product.

[0065] Mannich base dispersants are made from the reaction of
alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551,
which is incorporated herein by reference. Process aids and catalysts,
such as oleic acid and sulfonic acids, can also be part of the reaction
mixture. Molecular weights of the alkylphenols range from 800 to 2,500.
Representative examples are shown in U.S. Pat. Nos. 3,697,574; 3,703,536;
3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

[0067] Hydrocarbyl substituted amine ashless dispersant additives are well
known to one skilled in the art; see, for example, U.S. Pat. Nos.
3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197.

[0068] Preferred dispersants include borated and non-borated succinimides,
including those derivatives from mono-succinimides, bis-succinimides,
and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbyl
succinimide is derived from a hydrocarbylene group such as
polyisobutylene having a Mn of from 500 to 5000 or a mixture of such
hydrocarbylene groups. Other preferred dispersants include succinic
acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts,
their capped derivatives, and other related components. Such additives
may be used in an amount of 0.1 to 20 weight percent, preferably 0.5 to 8
weight percent.

Antioxidants

[0069] Antioxidants retard the oxidative degradation of base oils during
service. Such degradation may result in deposits on metal surfaces, the
presence of sludge, or a viscosity increase in the lubricant. One skilled
in the art knows a wide variety of oxidation inhibitors that are useful
in lubricating oil compositions. See, Klamann in Lubricants and Related
Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197, for
example.

[0070] Useful antioxidants include hindered phenols. These phenolic
antioxidants may be ashless (metal-free) phenolic compounds or neutral or
basic metal salts of certain phenolic compounds. Typical phenolic
antioxidant compounds are the hindered phenolics which are the ones which
contain a sterically hindered hydroxyl group, and these include those
derivatives of dihydroxy aryl compounds in which the hydroxyl groups are
in the o- or p-position to each other. Typical phenolic antioxidants
include the hindered phenols substituted with C6+ alkyl groups and
the alkylene coupled derivatives of these hindered phenols. Examples of
phenolic materials of this type 2-t-butyl-4-heptyl phenol;
2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol;
2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol;
2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecyl
phenol. Other useful hindered mono-phenolic antioxidants may include for
example hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in combination
with the instant disclosure. Examples of ortho-coupled phenols include:
2,2'-bis(4-heptyl-6-t-butyl-phenol); 2,2'-bis(4-octyl-6-t-butyl-phenol);
and 2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols include
for example 4, 4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).

[0071] Non-phenolic oxidation inhibitors which may be used include
aromatic amine antioxidants and these may be used either as such or in
combination with phenolics. Typical examples of non-phenolic antioxidants
include: alkylated and non-alkylated aromatic amines such as aromatic
monoamines of the formula R8R9R10N where R8 is an
aliphatic, aromatic or substituted aromatic group, R9 is an aromatic
or a substituted aromatic group, and R10 is H, alkyl, aryl or
R11S(O)xR12 where R11 is an alkylene, alkenylene, or
aralkylene group, R12 is a higher alkyl group, or an alkenyl, aryl,
or alkaryl group, and x is 0, 1 or 2. The aliphatic group R8 may
contain from 1 to 20 carbon atoms, and preferably contains from 6 to 12
carbon atoms. The aliphatic group is a saturated aliphatic group.
Preferably, both R8 and R9 are aromatic or substituted aromatic
groups, and the aromatic group may be a fused ring aromatic group such as
naphthyl. Aromatic groups R8 and R9 may be joined together with
other groups such as S.

[0072] Typical aromatic amines antioxidants have alkyl substituent groups
of at least 6 carbon atoms. Examples of aliphatic groups include hexyl,
heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups will not
contain more than 14 carbon atoms. The general types of amine
antioxidants useful in the present compositions include diphenylamines,
phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl
phenylene diamines. Mixtures of two or more aromatic amines are also
useful. Polymeric amine antioxidants can also be used. Particular
examples of aromatic amine antioxidants useful in the present disclosure
include: p,p'-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine;
phenyl-alphanaphthylamine; and p-octylphenyl-alpha-naphthylamine.

[0074] Preferred antioxidants include hindered phenols, arylamines. These
antioxidants may be used individually by type or in combination with one
another. Such additives may be used in an amount of 0.01 to 5 weight
percent, preferably 0.01 to 1.5 weight percent, more preferably zero to
less than 1.5 weight percent, most preferably zero.

Pour Point Depressants (PPDs)

[0075] Conventional pour point depressants (also known as lube oil flow
improvers) may be added to the compositions of the present disclosure if
desired. These pour point depressant may be added to lubricating
compositions of the present disclosure to lower the minimum temperature
at which the fluid will flow or can be poured. Examples of suitable pour
point depressants include polymethacrylates, polyacrylates,
polyarylamides, condensation products of haloparaffin waxes and aromatic
compounds, vinyl carboxylate polymers, and terpolymers of
dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers.
U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655,479;
2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pour point
depressants and/or the preparation thereof. Such additives may be used in
an amount of 0.01 to 5 weight percent, preferably 0.01 to 1.5 weight
percent.

Seal Compatibility Agents

[0076] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricating oils
include organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (butylbenzyl phthalate, for example), and polybutenyl succinic
anhydride. Such additives may be used in an amount of 0.01 to 3 weight
percent, preferably 0.01 to 2 weight percent.

Anti-Foam Agents

[0077] Anti-foam agents may advantageously be added to lubricant
compositions. These agents retard the formation of stable foams.
Silicones and organic polymers are typical anti-foam agents. For example,
polysiloxanes, such as silicon oil or polydimethyl siloxane, provide
antifoam properties. Anti-foam agents are commercially available and may
be used in conventional minor amounts along with other additives such as
demulsifiers; usually the amount of these additives combined is less than
1 weight percent and often less than 0.1 weight percent.

Friction Modifiers

[0078] A friction modifier is any material or materials that can alter the
coefficient of friction of a surface lubricated by any lubricant or fluid
containing such material(s). Friction modifiers, also known as friction
reducers, or lubricity agents or oiliness agents, and other such agents
that change the ability of base oils, formulated lubricant compositions,
or functional fluids, to modify the coefficient of friction of a
lubricated surface may be effectively used in combination with the base
oils or lubricant compositions of the present disclosure if desired.
Friction modifiers that lower the coefficient of friction are
particularly advantageous in combination with the base oils and lube
compositions of this disclosure. Friction modifiers may include
metal-containing compounds or materials as well as ashless compounds or
materials, or mixtures thereof. Metal-containing friction modifiers may
include metal salts or metalligand complexes where the metals may include
alkali, alkaline earth, or transition group metals. Such metal-containing
friction modifiers may also have low-ash characteristics. Transition
metals may include Mo, Sb, Sn, Fe, Cu, Zn, and others. Ligands may
include hydrocarbyl derivative of alcohols, polyols, glycerols, partial
ester glycerols, thiols, carboxylates, carbamates, thiocarbamates,
dithiocarbamates, phosphates, thiophosphates, dithiophosphates, amides,
imides, amines, thiazoles, thiadiazoles, dithiazoles, diazoles,
triazoles, and other polar molecular functional groups containing
effective amounts of O, N, S, or P, individually or in combination. In
particular, Mo-containing compounds can be particularly effective such as
for example Mo-dithiocarbamates, Mo(DTC), Mo-dithiophosphates, Mo(DTP),
Mo-amines, Mo (Am), Mo-alcoholates, Mo-alcohol-amides, etc. See U.S. Pat.
Nos. 5,824,627, 6,232,276, 6,153,564, 6,143,701, 6,110,878, 5,837,657,
6,010,987, 5,906,968, 6,734,150, 6,730,638, 6,689,725, 6,569,820; WO
99/66013; WO 99/47629; and WO 98/26030.

[0080] Useful concentrations of friction modifiers may range from 0.01
weight percent to 10-15 weight percent or more, often with a preferred
range of 0.1 weight percent to 5 weight percent. Concentrations of
molybdenum-containing materials are often described in terms of Mo metal
concentration. Advantageous concentrations of Mo may range from 10 ppm to
3000 ppm or more, and often with a preferred range of 20-2000 ppm, and in
some instances a more preferred range of 30-1000 ppm. Friction modifiers
of all types may be used alone or in mixtures with the materials of this
disclosure. Often mixtures of two or more friction modifiers, or mixtures
of friction modifier(s) with alternate surface active material(s), are
also desirable.

Viscosity Index Improvers

[0081] Viscosity index improvers (also known as VI improvers, viscosity
modifiers, and viscosity improvers) can be included in the lubricant
compositions of this disclosure. Preferably, the method of this
disclosure obtains improvements in fuel economy without sacrificing
durability by a reduction of high-temperature high-shear (HTHS) viscosity
to a level lower than 2.6 cP through reduction or removal of viscosity
index improvers or modifiers.

[0083] Suitable viscosity index improvers include high molecular weight
hydrocarbons, polyesters and viscosity index improver dispersants that
function as both a viscosity index improver and a dispersant. Typical
molecular weights of these polymers are between 10,000 to 1,500,000, more
typically 20,000 to 1,200,000, and even more typically between 50,000 and
1,000,000.

[0084] Examples of suitable viscosity index improvers are linear or
star-shaped polymers and copolymers of methacrylate, butadiene, olefins,
or alkylated styrenes. Polyisobutylene is a commonly used viscosity index
improver. Another suitable viscosity index improver is polymethacrylate
(copolymers of various chain length alkyl methacrylates, for example),
some formulations of which also serve as pour point depressants. Other
suitable viscosity index improvers include copolymers of ethylene and
propylene, hydrogenated block copolymers of styrene and isoprene, and
polyacrylates (copolymers of various chain length acrylates, for
example). Specific examples include styrene-isoprene or styrene-butadiene
based polymers of 50,000 to 200,000 molecular weight.

[0085] Olefin copolymers, are commercially available from Chevron Oronite
Company LLC under the trade designation "PARATONE®" (such as
"PARATONE® 8921" and "PARATONE® 8941"); from Afton Chemical
Corporation under the trade designation "HiTEC®" (such as "HiTEC®
5850B"; and from The Lubrizol Corporation under the trade designation
"Lubrizol® 7067C". Polyisoprene polymers are commercially available
from Infineum International Limited, e.g. under the trade designation
"SV200"; diene-styrene copolymers are commercially available from
Infineum International Limited, e.g. under the trade designation "SV
260".

[0086] In an embodiment of this disclosure, the viscosity index improvers
may be used in an amount of less than 2.0 weight percent, preferably less
than 1.0 weight percent, and more preferably less than 0.5 weight
percent, based on the total weight of the formulated oil or lubricating
engine oil.

[0087] In another embodiment of this disclosure, the viscosity index
improvers may be used in an amount of from 0.0 to 2.0 weight percent,
preferably 0.0 to 1.0 weight percent, and more preferably 0.0 to 0.5
weight percent, based on the total weight of the formulated oil or
lubricating engine oil.

[0088] When lubricating oil compositions contain one or more of the
additives discussed above, the additive(s) are blended into the
composition in an amount sufficient for it to perform its intended
function. Typical amounts of such additives useful in the present
disclosure are shown in Table 1 below.

[0089] It is noted that many of the additives are shipped from the
additive manufacturer as a concentrate, containing one or more additives
together, with a certain amount of base oil diluent. Accordingly, the
weight amounts in the table below, as well as other amounts mentioned in
this specification, are directed to the amount of active ingredient (that
is the non-diluent portion of the ingredient). The weight percent (wt %)
indicated below is based on the total weight of the lubricating oil
composition.

[0090] The foregoing additives are all commercially available materials.
These additives may be added independently but are usually precombined in
packages which can be obtained from suppliers of lubricant oil additives.
Additive packages with a variety of ingredients, proportions and
characteristics are available and selection of the appropriate package
will take the requisite use of the ultimate composition into account.

[0091] The following non-limiting examples are provided to illustrate the
disclosure.

[0093] Among the features of the compositions of the disclosure is that
there has been demonstrated both unexpected combination of wear and fuel
efficiency performance. For instance, fuel economy can be improved by at
least 0.4% as measured in the M111 FE engine test and while the wear
performance is improved relative to the comparison oils.

[0094] Performance evaluation of the formulations is given in Tables 3-11.
The following engine tests were performed to measure wear and fuel
economy of the engine oil lubricant composition of the present
disclosure: TU3M (CEC L-038-94), M111FE (CEC L-054-96), Sequence IIIG
(ASTM D7320), Sequence IVA (ASTM D6891), Sequence VID (ASTM D7589),
OM646LA (CEC L-099-08), Caterpillar 1M-PC (ASTM D6618) and Sequence VIII
(ASTM D6709); all of which are incorporated herein by reference. HTHS
viscosity was measured using ASTM D4683 which is incorporated herein by
reference.

[0099] The parameters listed in Table 7 above, and methods for determining
same, are more fully described in ASTM D7589. In this case a slightly
modified version of ASTM D7589 was run; two additional samples were taken
during the test compared to the ASTM method.

[0102] The parameters listed in Table 10 above, and methods for
determining same, are more fully described in ASTM D6709.

[0103] As can be seen from the foregoing Tables, the composition of the
disclosure provided improved or equivalent antiwear properties while
providing a substantial improvement in fuel economy when compared to the
other oils identified. In the foregoing Tables, the blanks for engine
test properties indicate that no data was available for that particular
test.